THE DIRIGIBLE BALLOON ACHIEVED
By this war, France, the home of the balloon, was brought keenly to realize the advantages and the limitations of such flying-machines; and it was but natural, under the circumstances, that as soon as peace was restored, efforts should be made there to produce a dirigible balloon, or some other form of dirigible flying-machine. Giffard, as we have seen, had been fairly successful; and now M. Dupuy de Lome, chief naval constructor of France, took up the problem. He constructed a balloon with a cigar-shaped envelope one hundred and twenty feet long and fifty feet in diameter. Beneath this was a rudder placed in the same position as that of a ship; and suspended still further below was a large car fitted with a two-bladed screw-propeller, thirty feet in diameter. Manual labor was to be used for turning this screw, two relays of four men each relieving each other at the work. An ascent was made in February, 1872, with fourteen persons in the car, who, by working in relays, demonstrated that a speed of about seven miles an hour could be maintained in any direction in still air. As the wind was blowing about thirty miles an hour at the time, however, the course of the balloon could only be deflected, and the main object of the ascent—the return to Paris—could not be accomplished. In short, De Lome's balloon demonstrated little more than had been accomplished by Giffard with his steam-driven balloon. Both had shown that with sufficient power the balloon could be made to travel in any direction in still air, but neither had been able to make headway against a strong wind.
It was estimated at the time of Dupuy de Lome's ascent, that had a steam-engine of a weight corresponding to that of the eight workmen been used, at least twice the power could have been obtained. But steam was considered too dangerous, and some other motive power which combined lightness with power seemed absolutely essential. The electric motor gave promise of success in this direction, and in 1883 the two Tissandier brothers in France applied such a motor to a balloon that was able to make headway against a seven-mile breeze, but was still far from fulfilling the requirements of an entirely dirigible balloon. Two years later the motor-driven balloon La France, of Renard and Krebs, attained a speed of fourteen miles an hour, and showed a distinct advance over all preceding models.
Meanwhile motors were being reduced in weight and increased in power, and the hearts of aviators and balloonists were cheered by the fact that the light metal, aluminum, was steadily growing cheaper. Visions of an all-aluminum balloon were constantly before the minds of the inventors, and in 1894 such dreams took practical form in a balloon whose construction was begun by Herr Schwartz, under the auspices of the German Government. This balloon was of most complicated construction, depending for its lifting power upon the gas-filled aluminum tank, but utilizing for its steering-gear many of the features of the aeroplane. It was essentially a balloon, not a flying-machine, however, with a ten to twelve horse-power benzine-engine actuating four propelling screws.
TWO FAMOUS FRENCH WAR BALLOONS.
The lower figure the dirigible war balloon "La Patrie," which manœuvered on the Eastern boundary of France, and which was blown away and lost taking a northwesterly direction which probably landed it ultimately in the Arctic Sea—in 1908. The upper figure represents M. Deutsch's dirigible balloon "Ville de Paris" which was sent to the frontier to take the place of the lost "Patrie."
Before the balloon was completed Herr Schwartz died, but his plans were known to his wife, and, although considerably altered, were carried to completion. When all was finished, Herr Jaegels, an engineer who had had no experience as an aeronaut, volunteered to make an ascent and this metal ship-of-promise was launched. At first it rose rapidly and appeared to be making good progress against a strong wind; but suddenly it stopped, descended rapidly, and was smashed to pieces, the aeronaut saving himself by jumping just before it touched the ground. It developed later that he had lost control of the machine, simply because the machinery was too complicated for a single operator to handle. On discovering this, Herr Jaegels, confused for the moment, threw open the valve, causing the balloon to descend too rapidly. Thus the fruit of years of study and labor and the expenditure of fifty thousand dollars in money resulted in only about six minutes of actual flight.
To most persons this experiment of the aluminum balloon would seem to have been a dismal failure, but it was not so regarded by the advocates of the dirigible balloon. The flight of the balloon, to be sure, was far from a success; but this was attributed to improper management rather than to any inherent defect in the balloon itself, or in the principle upon which it was constructed. Instead of being discouraged, therefore, the school of balloonists, who had lost some of their prestige of late by the performances of the flying-machines of Maxim and Langley, undertook, through their enthusiastic representative, Count Zeppelin, the construction of the largest, most expensive, and most carefully built dirigible balloon heretofore constructed. This balloon was of proportions warranting the name of "air-ship." The great cigar-shaped body was almost four hundred feet in length, and thirty feet in diameter—the proportions of a fair-sized ocean liner—and like the hull of its ocean prototype, was divided into compartments—seventeen in number, and gas-tight. Its frame-work was of aluminum rods and wires, and the skin of the envelope was made of silk, coated with india-rubber. It was equipped with four aluminum screws, and two aluminum cars were placed below the body at a considerable distance apart. The motive power was supplied by benzine motors, selected because of their lightness.
The company for constructing this balloon was capitalized at about two hundred thousand dollars, the cost of the shed alone, which rested on ninety-five pontoons on the surface of the lake of Constance, near the town of Manzell, being fifty thousand dollars. July 2nd, 1910, the count and four assistants in the cars, started on the maiden voyage. The balloon rose and made headway at the rate of eighteen miles an hour, responding readily to the rudder, but soon broke or deranged some of the steering-gear so that it became unmanageable and descended at Immerstaad, a little over three miles from the starting-point. Considering the amount of thought, care, and money that had been expended upon it, its performance could hardly be looked upon as a startling success. By the advocates of the aeroplane principle it was considered an utter failure.
THE ZEPPELIN DIRIGIBLE BALLOON.
Count Zeppelin's famous balloons are of the semi-rigid type, being cased in thin loops of aluminum. The wing-like projections at the sides add greatly to the stability and dirigibility of the balloon. The problem of housing has been met by erecting a structure over the water. It is planned to have a balloon house that will revolve and thus facilitate the introduction of the balloon whatever the direction of the wind. With the above stationary house this is a difficult manœuvre if the wind chances to blow laterally.
But while Count Zeppelin was experimenting with his ponderous leviathan air-ship, a kindred spirit, the young Brazilian, M. Santos-Dumont, was making experiments along similar lines, but with balloons that were mere cockle-shells as compared with the German monster. The young inventor had come to Paris from his home in South America backed by an immense fortune, and by a fund of enthusiasm, courage, and determination unsurpassed by any aerial experimenter in any age. He began at once experimenting with balloons of different shapes, with screws and paddles, and, perhaps most important of all, with the new, light petroleum-motors just then being introduced for use on automobiles, electricity not having proved a success in aerial experiments.
His first balloon, No. 1, built in 1898, was devoid of any particularly novel features. His No. 2 showed some advancement, and his No. 3, while a decided improvement, still came far short of answering the requirements of a dirigible balloon. But the young experimenter was learning and profiting by his failures—and, incidentally, was having hairbreadth escapes from death, meeting with many accidents, and being severely injured on occasion.
About this time a prize of one hundred thousand francs was offered by M. Deutsch to the aeronaut who should ascend from a specified place in a park in Paris, make the circuit of the Eiffel Tower, and return to the starting-point within half an hour. With the honor of capturing this prize as an additional incentive, Santos-Dumont began the construction of his fourth balloon, the Santos-Dumont No. 4. In this balloon everything but bare essentials was sacrificed to lightness, even the car being done away with, the aeronaut controlling the machinery and directing the movements of the balloon from a bamboo saddle. But an accident soon destroyed this balloon, and a fifth was hastily constructed. With this the enthusiastic aeronaut showed that he was almost within grasping distance of the prize in a series of sensational flights between the first part of July and the first week in August. The tower was actually rounded, but on the return trip the balloon collided with a high building in the Rue Alboni and was wrecked, the escape of the aeronaut without a scratch being little short of miraculous.
Nothing daunted, the inventor began the construction of Santos-Dumont No. 6 immediately, finishing it just twenty-eight days after the construction of No. 5. A peculiarity of this balloon was that it was barely self-sustaining except when forced through the air by the propeller. The long cigar-shaped gas-bag was relatively small, and was filled to its limit of capacity with gas, while the lifting power was counterbalanced by the operator, car, engine, and ballast, so that the entire structure weighed practically the same as the air it displaced. At the stern was a powerful propeller. Obviously, then, if the long spindle-shaped machine was tilted upward at the forward end, and the propeller started, it would be driven upward; while if the forward end was lowered the propeller would drive it downward. If it was balanced so as to be perfectly horizontal, it would be forced forward in a horizontal direction. Deflections to right and to left were obtained by the ordinary type of vertical rudder; and thus any direction could be taken.
AN ENGLISH DIRIGIBLE BALLOON.
The photograph here reproduced gives a very vivid impression of the cumbersome nature of balloons of this modern type, and suggests the difficulties to be met in housing them safely when not in use.
To obtain the desired angle of inclination, Santos-Dumont made use of a sliding weight, and with this he guided his balloon upward and downward by shifting its position. Thus, although this balloon was a veritable balloon rather than a "flying-machine" proper, it really lacked the one essential common to balloons: it would not rise until propelled by mechanical means. It lacked the requisite of the flying-machine, however, in that it was not "many times heavier than the air." After giving this new balloon several preliminary trials, which included such exciting incidents as collisions with a tree in the Bois du Boulogne, an official attempt was made on October 29th, 1800. Above the heads of the gaping thousands, who, to a man, wished the daring navigator success, the balloon rounded the tower, and in twenty-nine minutes and thirty seconds from the moment of starting—thirty seconds less than the prescribed time-limit—the trip was successfully terminated.
This voyage must be considered as marking an epoch in aerial navigation. The dirigible balloon was accomplished. A decided step forward in the conquest of the air had been made, although from a practical standpoint this step was confessedly a short one. For while No. 6 could be propelled in any direction under ordinary conditions, carrying a single passenger, it was on the whole more of a toy ship than a practical sailing-craft. Nevertheless, its performance was a decided victory for the balloon over the flying-machine. No flying-machine of whatever type had ever even approached the performance of Santos-Dumont No. 6, which had carried a man on a voyage in the air, traveling with the wind, against it, and with the wind on either quarter at every possible angle at various times during the journey. And yet there were few scientists, indeed, if any, who considered that the problem of aerial navigation was solved; and to a large number Santos-Dumont's performance seemed little more than an extension of Giffard's idea, made possible by improved machinery not available half a century ago. To them it was the triumph of the energy, skill, and courage of an individual, not the triumph of a principle—which, after all, is the absolute essential.
ENGLISH (LOWER FIGURE) AND AMERICAN DIRIGIBLE WAR BALLOONS AND A WRIGHT AEROPLANE.
The above figures are introduced on one page for the purpose of comparison and contrast. The American balloon is the Baldwin airship. The essential clumsiness of a lighter-than-air craft, as contrasted with the relative gracefulness and manageableness of the aeroplane, is strikingly suggested by this illustration.
Since the successful performance of Santos-Dumont in rounding the Eiffel Tower many other dirigible balloons have been constructed, not only in America and in Europe by various inventors, but by the Brazilian aeronaut himself. The most remarkable of these is the Zeppelin II, the fifth creation of the indomitable Count Zeppelin. In principle and general lines of construction this balloon closely resembles the one described a few pages back. Its best performance, however, is more remarkable. Starting from Lake Constance on the night of May 29th, 1909, and sailing almost directly northward regardless of air currents, the balloon reached Bitterfield, a few miles beyond Leipzig, four hundred and sixty-five miles from the starting-point, the following evening. Turning back at this point, without alighting, it had almost completed its return trip, when on coming to the ground for a supply of fuel it was injured by collision with the branches of a tree. The injury sustained, while delaying and marring the voyage, did not prevent the balloon from completing its eight-hundred-and-fifty mile voyage, and establishing a new record for dirigibles.
This and sundry other flights amply demonstrated the dirigibility and relative safety of the balloon under varying atmospheric conditions. But the difficulties that attend the management of such a craft when not high in air were again vividly illustrated when, in April, 1910, the Zeppelin II., was totally wrecked while at anchor by the force of a gale which it might easily have outridden had it been beyond the reach of terrestrial obstacles.
X
THE TRIUMPH OF THE AEROPLANE
ALTHOUGH the dirigible balloon in the hands of Santos-Dumont gained a decisive victory over all mechanical methods of flight theretofore discovered, even the inventor himself considered it rather as a means to an end, than the end itself. That end, it would seem, must be a flying-machine, many times heavier than the atmosphere, but able by mechanical means to lift and propel itself through the air. The natural representative of this kind of flying-machine, the bird, is something like a thousand times as heavy as the air which its bulk displaces. The balloon, on the other hand, with its equipments and occupants, must necessarily be lighter than air; and as the ordinary gas used for inflating is only about seven times lighter than the atmosphere, it can be readily understood that for a balloon to acquire any great amount of lifting power it must be of enormous proportions. To attempt to force this great, fragile bulk of light material through the atmosphere at any great rate of speed is obviously impossible on account of the resistance offered by its surfaces. On the other hand, any such structure strong enough to resist the enormous pressure at high speed would be too heavy to float.
THE AEROPLANE OF M. SANTOS DUMONT.
M. Santos Dumont's chief fame as an aviator is based on his flights with a dirigible balloon. He has experimented extensively, however, with the heavier-than-air type of machine, though none of his flights with this apparatus has been record-breaking.
These facts are so patent that it is but natural to inquire how the balloonists could ever have expected to accomplish flight at more than a nominal rate of speed; and, on the other hand, it might be asked, naturally enough, how the aviators expected to fly with aeroplane machines at least a thousand times heavier than the air. In reply, the aviators could point to birds and bats as examples of how the apparently impossible is easily accomplished in nature; while the balloonists could simply point to their accomplished flights as practical demonstrations. The aviators could point to no past records of accomplishments, but nevertheless they had good ground for the faith that was in them, and as we shall see were later to justify their theories by practical demonstrations.
Everybody is aware that there is an enormous difference in the lifting power of still air and air in motion, and that this power is dependent upon velocity. The difference between the puff of wind that barely lifts a thin sheet of paper from the table, and the tornado that uproots trees and wrecks stone buildings, is one of velocity. Obviously, then, moving air is quite a different substance from still air when it comes to dealing with aeronautics.
One of the most familiar examples of the lifting power of moving air is that of the kite. An ordinary kite is many times heavier than the air and has no more tendency to rise in the air than a corresponding weight of lead under ordinary conditions. Yet this same kite, if held by a string with its surfaces inclined to the wind at a certain angle, will be lifted with a force proportionate to the velocity of the wind and the size of the surfaces. On a windy day the kite-flyer holding the string and standing still will have his kite pushed upward into the air by the current rushing beneath its surface. On a still day he may accomplish the same thing by running forward with the kite-string, thus causing the surface of the kite to "slide over" the opposing atmosphere. In short, it makes no difference whether the air or kite is moving, so long as the effect of the current rushing against the lower surface is produced. Obviously, then, if in place of the kite-flyer holding the string and running at a certain speed, some kind of a motor could be attached to the kite that would push it forward at a rate of speed corresponding to the speed of the runner, the kite would rise—in short, would be converted into a flying-machine.
Looked at in another way, the action of the air in sustaining a body in motion in the air has been compared by Professor Langley to the sustaining power of thin ice, which does not break under the weight of a swiftly gliding skater, although it would sustain only a small fraction of his weight if he were stationary. Supposing, for example, the skater were to stand upon a cake of ice a foot square for a single second; he would sink, let us say, to his waist in the water. On a cake having twice the surface area, or two square feet, he would sink only to his knees; while if the area of the cake is multiplied ten times the original size, he would scarcely wet his feet in the period of a second. Now supposing the cake to be cut into ten cakes of one square foot each, placed together in a line so that the skater could glide over the entire ten feet in length in one second. It is evident that he would thus distribute his weight over the same amount of ice as if the cakes were fastened together in a solid piece.
"So it is with the air," says Professor Langley. "Even the viewless air possesses inertia; it cannot be pushed aside without some effort; and while the portion which is directly under the air-ship would not keep it from falling several yards in the first second, if the ship goes forward so that it runs or treads on thousands of such portions in that time, it will sink in proportionately less degree; sink, perhaps only through a fraction of an inch."
It is evident, therefore, that if, at a given speed, the horizontal wings of an air-ship would keep it from falling more than a fraction of an inch in a second, by increasing the speed sufficiently and giving the wings an upward inclination, the air-ship instead of falling might actually rise. And this, as we shall see presently, is just what the flying-machines of Sir Hiram Maxim and Professor Langley and of the Wright brothers and their imitators did do.